The present invention relates to an apparatus and a method for producing a plait-like portion on a tubular packaging casing according to the preamble of independent claims 1 and 10.
In particular, the invention concerns an apparatus for producing a plait-like portion on a tubular packaging casing which accommodates a filling material in particular sausage meat, wherein the plait-like portion is at least approximately free of filling material and comprises along a longitudinal plait-axis. The apparatus comprises a first displacer unit with a first pair of displacer elements being reversibly movable perpendicular to the longitudinal plait-axis between an opened and a closed position. A displacer clearance is being created between the first pair of displacer elements, which surrounds the longitudinal plait-axis and in which the tubular packaging casing is being gathered, when the first pair of displacer elements is in the closed position. Beyond that, the apparatus comprises a second displacer unit with a second pair of displacer elements also being reversibly movable perpendicular to the longitudinal plait-axis between an opened and a closed position. Again, a displacer clearance is being created between the second pair of displacer elements, which surrounds the longitudinal plait-axis and in which the tubular packaging casing is being gathered, when the second pair of displacer elements is in the closed position. The second displacer unit is reversibly movable parallel to the longitudinal plait-axis between a narrow position in which the first displacer unit is adjacent to the second displacer unit, and a spread position in which the second displacer unit is moved away from the first displacer unit. Furthermore, the apparatus comprises a first drive unit for the movement of the first and second pair of displacer elements between the opened and closed position. The first drive unit comprises an adjustment device rotatable around a pivot axis essentially parallel to the longitudinal plait-axis.
Moreover, the invention concerns method for producing a plait-like portion on a tubular packaging casing which accommodates a filling material in particular sausage meat, wherein the plait-like portion is at least approximately free of filling material and extends along a longitudinal plait-axis. The method includes the steps of conveying of a filling material into a tubular packaging casing and constricting the filled tubular packaging casing by moving a first pair of displacer elements of a first displacer unit and a second pair of displacer elements of a second displacer unit from an opened into a closed position by means of a first drive unit. Furthermore, a displacer clearance is created between the first and second pair of displacer elements surrounding the longitudinal plait-axis, in which the tubular packaging casing is being gathered when the first and second pair of displacer elements are in the closed position. Thereafter, a plait-like portion is produced by moving the second displacer unit parallel to the longitudinal plait-axis away from a narrow position in which the second displacer unit is adjacent to the first displacer unit, into a spread position in which the second displacer unit is away from the first displacer unit.
It is the usual practice in sausage production, to use for example automatic clipping machines for filling e.g. sausage meat via a filling tube into a flexible packaging material, like a tubular casing which is closed by a closure means, referred to as closing clip, at the first end. After the filling operation is concluded, a gathered plait-like portion, which is free of filling material, is formed by two displacer units. Two more clips are then applied to that plait-like portion, a first closing clip in order to close the second end of the filled packaging material and a second closing clip in order to close the first end of the subsequent sausage product. Thereafter, said plait-like portion is severed between said two clips creating one complete sausage product and packaging material closed at its first end to be filled, in order to form the next sausage product. Such a practice for producing sausages is disclosed, for example, by EP-patent application 1 967 073 A1 or DE-Utility model 20 2006 012 324 U1.
After the filling process, the sausage products can be sometimes subjected to further processing, for example in a smoking chamber or they are just being packed in a box for shipping.
The different sausage products are typically characterized by a number of parameters, such as caliber (i.e. the actual diameter of the sausage product), overall length, specific type of the filling material as well as packaging casing material etc. Also, it is possible to vary the density of the filling material, in order to produce loosely filled or tightly filled sausage products, by injecting more or less filling material into the casing. However, in case of a tightly filled sausage product, these sausage products are rather prone to damages on the casing, due to the high pressure inside the sausage product and the often thin and sensitive casing material. Impacts, falls and other kinds of careless handling can result inevitable in notable damages to the sausage products, which lead to outcast and unnecessary costs. A particular problem in this context constitutes within the actual procedure of constricting the casing by means of the two displacer units and forming the plait-like portion out of the tubular packaging casing. Depending on the above mentioned parameters, in particular, sensitive casing material or “normal” casing material which is filled with sausage meat at high pressure may be damaged during the constricting process when executed at a “normal” speed. Moreover, the casing material may be also damaged during forming the plait-like portion.